This invention relates generally to roller bearing cages and, more particularly, to roller bearing cages of "sigma" configuration.
Roller bearings commonly employ separators, retainers or cages to maintain separation and alignment of the rollers. Although the terms are frequently used interchangeably, the term "cage" is often used to describe a device that retains the rollers both radially and axially. Thus, a roller bearing cage prevents rollers from moving axially or radially out of the cage, allowing the cage and rollers to be handled as a bearing subassembly.
One particular type of roller bearing cage is known as a sigma cage. As illustrated in FIG. 1, a typical sigma cage 10 has annular end rims 12 and 14, axially spaced apart along a common axis, joined together by crossbars 16 to form slots 18 for receiving rollers, not shown. Crossbars 16 have a central portion 20 offset radially inwardly from laterally outward portions 22 and 24 such that, when viewed in longitudinal section, end rims 12 and 14 and crossbars 16 resemble the Greek letter "sigma".
End rims 12 and 14 extend radially as end flanges 26 and 28, respectively. End flanges 26 and 28 provide stop surfaces which assist slots 18 to ensure that axial movement of the rollers is restricted. Edge surfaces on central portion 20 prevent radially inward movement of the rollers and edge surfaces of laterally outward portions 22 and 24 prevent radially outward movement of the rollers.
In some applications, a significant axial offset is required between the roller pockets (slots) and the end flanges of the cage. Such offset materially affects the axial containment of the rollers because the end flanges no longer provide stop surfaces proximate to the slots. As a result, roller loss can occur during handling of the cage before installation or upon installation of the bearing in the housing.
The foregoing illustrates limitations known to exist in present roller bearing cages of sigma configuration. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.